====== Variability as a Service : Outsourcing Variability Management in Multi-tenant SaaS Applications ======

===== Abstract =====

In order to reduce the overall application expenses and time
to market, SaaS (Software as a Service) providers tend to outsource
several parts of their IT resources to other services providers. Such out-
sourcing helps SaaS providers in reducing costs and concentrating on
their core competences: software domain expertises, business-processes
modeling, implementation technologies and frameworks etc. However,
when a SaaS provider offers a single application instance for multiple
customers following the multi-tenant model, these customers (or ten-
ants) requirements may differ, generating an important variability man-
agement concern. We believe that variability management should also
be outsourced and considered as a service. The novelty of our work is
to introduce the new concept of Variability as a Service (VaaS) model.
It induces the appearance of VaaS providers. The objective is to relieve
the SaaS providers looking forward to adopt such attractive multi-tenant
solution, from developing a completely new and expensive variability so-
lution beforehand. We present in this paper the first stage of our work:
the VaaS meta-model and the VariaS component.